RE: Cable Modems

["Matthew L. Mandalek" <mandalek@hlc.net>]

  The bandwidth that is available for use is about 30Meg total.  The network must be built in small enough segments that the users do not get a bottle neck, just as with a LAN.
  
  There is a problem with Upstream communications pickup noise on the line and this is the reason that the transmissions in that direction will be somewhat slower then the Downstream communications from the cable companies network head.  When the network is designed correctly, every house could experience full T1 availability at all times.  Remember that the Upstream communications are minimal as they only make request most of the time, and the Downstream traffic is what takes up most of the bandwidth.
  
  
  
  ----------
  From:  Justin Hannah[SMTP:sparc@inetnebr.com]
  Sent:  Wednesday, February 14, 1996 9:54 AM
  To:  Multiple recipients of list
  Subject:  Cable Modems
  
  I am still confused as to how a cable modem is supposed to be
  bi-directional.  The way I understand most cable systems is that there are
  many amplifiers (in theory unidirectional), splitters, and other things in
  the way of a signal going uphill to the cable company.  Wouldn't this
  require modifications to the entire cable infrastructure?
  
  Perhaps a system similar to the UDBC satellite and DSS systems operate would
  be employed.  Supposedly, when internet connectivity is employed on these
  systems, a dialup modem (usually between 1200 and 9600bps) would call the
  satellite company to send data and the receive data comes thru the satellite.
  
  Another question; if "everyone" has this 10mbps bandwidth from the cable
  company, this would force the ISPs that carry web pages and other services
  that can be accessed remotely to employ a much higher speed connection.
  Perhaps 20x or more, just like how T1 lines (1.544mbps, the most common
  connection for ISPs) are compared to the standard (28.8kbps) modems used on
  the desktop.
  
  - sparc@inetnebr.com
    Justin Hannah